栈（stack）是先进后出的数据结构。单调栈在入栈时通过一定规则保持栈内元素有序（单调递增或单调递减），从而把「找左侧/右侧第一个更大/更小元素」从 O(n²) 降到 O(n)。
Some experts say this signals the start of a new space race – not just for prestige, but to build a long-term presence on the Moon, tap its resources and use it as a stepping stone to Mars. We speak to the BBC’s Science Editor, Rebecca Morelle.，更多细节参见Line官方版本下载
，详情可参考heLLoword翻译官方下载
// it is ok to write more data，详情可参考safew官方版本下载
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